You have have to execute (require 'cedet) if cedet-version doesn't
immediately work.

Personally, I find it the easiest to run CEDET from source, because I use some
of the features that don't come with the bundled version, in order to do that, I
clone the repository and set up a early in my init.el configuration

;; Load a custom version of cedet, if available(when(file-exists-p "~/src/elisp/cedet/cedet-devel-load.el")(load "~/src/elisp/cedet/cedet-devel-load.el"))

Unfortunately there is no MELPA or ELPA package for this, though work is
underway to merge CEDET into Emacs itself entirely, so that it can be a native
feature instead of half-missing.

Once you've set up CEDET as above, check out cedet-version again and see if
it's the same (or different, as long as its installed you should be good to go).

3 How to set up Semantic in your Emacs configuration

Semantic has a lot of different minor modes that can be toggled on and off as
needed, they follow the form of

global-semantic-*-mode

These can be used individually, but the best way to configure these is to set
the semantic-default-submodes variable to be a list of the modes you want to
enable, the default value for this variable is

'(global-semantic-idle-scheduler-mode global-semanticdb-minor-mode)

Which is fine, but you may want to add modes to it

(setq semantic-default-submodes
'(;; Perform semantic actions during idle time
global-semantic-idle-scheduler-mode
;; Use a database of parsed tags
global-semanticdb-minor-mode
;; Decorate buffers with additional semantic information
global-semantic-decoration-mode
;; Highlight the name of the function you're currently in
global-semantic-highlight-func-mode
;; show the name of the function at the top in a sticky
global-semantic-stickyfunc-mode
;; Generate a summary of the current tag when idle
global-semantic-idle-summary-mode
;; Show a breadcrumb of location during idle time
global-semantic-idle-breadcrumbs-mode
;; Switch to recently changed tags with `semantic-mrub-switch-tags',;; or `C-x B'
global-semantic-mru-bookmark-mode))